a. Field of the Invention
The instant invention is directed toward a universal cell carrier, including a universal cell carrier for housing an ablation element, such as for use in an epicardial ablation device.
b. Background Art
In a normal heart, contraction and relaxation of the heart muscle (myocardium) takes place in an organized fashion as electrochemical signals pass sequentially through the myocardium from the sinoatrial (SA) node located in the right atrium to the atrialventricular (AV) node and then along a well defined route which includes the His-Purkinje system into the left and right ventricles. Atrial fibrillation results from disorganized electrical activity in the heart muscle, or myocardium. An increasingly common medical procedure for the treatment of certain types of cardiac arrhythmia and atrial arrhythmia involves the ablation of tissue in the heart to cut off the path for stray or improper electrical signals.
Ablation may be performed either from within the chambers of the heart (endocardial ablation) using endovascular devices (e.g., catheters) introduced through arteries or veins, or from outside the heart (epicardial ablation) using devices introduced into the chest. The ablation devices are used to create elongated transmural lesions—that is, lesions extending through a sufficient thickness of the myocardium to block electrical conduction—which form the boundaries of the conductive corridors in the atrial myocardium. The ablation devices create lesions at particular points in the cardiac tissue by physical contact of the cardiac tissue with an ablation element and the application of energy.
One difficulty in obtaining an adequate ablation lesion is the constant movement of the heart, especially when there is an erratic or irregular heart beat. Another difficulty in obtaining an adequate ablation lesion is retaining uniform contact with the cardiac tissue across the entire length of the ablation element surface. Without sufficiently continuous and uniform contact, the associated ablation lesions may not be adequate.
An epicardial ablation device may be used to create uniform, continuous, linear lesions during cardiac ablation. The device may be positioned securely around a patient's atrium while the ablation elements apply energy (e.g., high intensity focused ultrasound energy) to the targeted tissue. The ablation elements are retained by a cell carrier. In a conventional epicardial ablation device, there are any number of unique cell carriers that must be produced for use in a single epicardial ablation device. For example, the tops (e.g., covers) of mid cell carriers must be produced with varying heights in order to provide varying clearances for elements (e.g., wires, tubes) disposed adjacent the cell carrier. In addition to producing a number of unique tops for mid cell carriers, a unique distal cell carrier and unique proximal cell carrier must be produced for use in a single epicardial ablation device. Distal and proximal cell carriers must each be configured to provide for attachment of a leash and an entry point for a fluid tube in a proper orientation that may still allow for sufficient shaping of the device.